3-thienyl thioethers



Patented Dec. 4, i951 3-THIENYL THIOETHERS John W. Brooks, Wenonah, and Sigmund J.

Lukasiewicz, Woodbury, N. J assignors to Socony-Vacuum Oil Company,slncorporated, a

corporation of New York No Drawing. Original application December 13,

1947, Serial No. 791,652. Divided and this application November 22, 1948, Serial No. 61,524

1 claim. -(o1. 260-329)" This invention relates to a group of new chemical compounds, namely, 3-thienyl thioethers. More specifically, the present invention is directed to an improvement of viscous mineral oil fractions by incorporation therein of a small proportion sumcient to improve the properties thereof of one or more of the aforesaid compounds. 7 7

As is well known to those familiar with the art, substantially all of the numerous fractions obtained from mineral oils and refined for their various uses are susceptible to oxidation. The susceptibility of an oil fraction to oxidation and the manner in which oxidation manifests itself within the oil varies withthe type and degree of refinement to which the oil has been subjected and with the conditions under which it is used or tested. That is, the products formed in an oil fraction as a result of oxidation and the degree to which they are formed depend on the extent to which the various unstable constituents or constituents which may act as oxidation catalysts have been removed by refining operations and also upon the conditions of use.

'The present invention is predicated upon the discovery that a group of new chemical compounds, the 3-thienyl thioethers, greatly improve the oxidation characteristics of mineraloil fractions by the incorporation therein of minor proportions of these compounds. It has been found thatby the addition of a 3-thieny1 thioether to a viscous mineral oil fraction, the development of undesirable products and properties, such as acid,sludge, discoloration, and corrosiveness to ward alloy-bearing metals, normally encountered under conditions of use, has been substantially inhibited.

The compounds of this invention may be designated by the general formula:

Us-R

where R represents an alkyl, aralkyl, aryl, or alicyclic group. These compounds may suitably be prepared by the action of an appropriate 40 v tothe mode of addition impliedby Markownie- 3-thiophenethio1 is replaced by the alkyl, aralkyl,

aryl, or alicyclic group of the organic halide employed to yield the desired 3-thienyl thioether. The reaction thus takes place in accordance with the following general equation:

' it ee es Q f re h s ihs 9'9! 2 .J poundsof this invention comprises the reaction of an olefin with 3-thiophenethiol. The reactionfrnay bev effected either in the presence of an alkylation catalyst'such'as boron ,trifluoride, sulfuricv acid, silica-alumina composite, boron trifluoride-etherate, and other complexes of boron trifluoride; or where a highly reactive olefin'is employed, such as isobutylene, styrene, etc.) the reaction may be efiected in the absence of a catalyst, even at room temperature. In general, the temperature at which the above reaction is carried out will be between about 20 C. and about 250 C. The particular conditions of tempera ture employed will depend in part on the nature of the olefin used. Olefins containing a double bond connected to a tertiary carbon atom" react withB-thiophenethiol at relatively lower temperatures in the above range. On the other hand, whencompoun ds having an olefinic bond not connected to'a tertiary carbon atom are employed, relatively higher temperatures in the upper portion of the above range must be used. The reaction of olefins with 3-thiophenethiol under the above conditions appears to be a selective reaction in which the mercapto group is involved, since little or no alkylation of the thiophene nucleus has' been found to take place; The aforementioned reactant of 3-thiophenethiol may be prepared by the procedure described in Chem. Inds. 60, 593-5, 620 (1947) or by any other feasible method.

Any of the commonly employed alkylation catalystsare contemplated for use in promoting the reaction of 3-thiophenethiol with an olefin. The nature 'of the reaction product obtained .appears to depend upon whether the reaction' is carried out in the absence or presence of en alkylation catalyst. Thus, the manner of addi-'- tion of the olefin tome thiophenethiol employed will, in the absence of a catalyst, be contrary koffis rule. In the presence of an alkylation catalyst such as sulfuric acid, silica-alumina composites, .boron trifluoride and complexes thereof, the mode of addition of olefin to 3- thio phenethiolv follows Markownikoffs rule.- The distinction between the nature of the products obtained in each instance will be readily apparent from the following general equations indicating the course ofreaction.

of Equation 11,, the rule was not followed. Thus, the products formed from catalytic and non-1 catalytic alkylation reactions will generally be of a difierent structure. However, in every instance, the product is a 3-thienyl thioether.

The above alkylation reactions will usually be carried out with a molar ratio of thiophenethiol to olefin of between about 2 to. 1 and about, 1, to and generally in the presence of an alkylation catalyst of which the boron trifluoride complexes may be considered to b a preferred embodiment. In particular, boron trifluorideeether-e ate has been found to be an efiective ca alyst, in promoting the reaction.

The nature of the organic substituent group present in the 3-thienyl thioethers described herein may be either saturated or unsaturated, may be either a straight chain or branched chain, monocyclic or polycyclic group, may contain one or more aromatic groups and may have attached thereto through a thioether linkage one or more thienyl groups. Thus, the organic substituent may be a thienyl thioalkyl group. Representative of the alkyl', aryl, alicyclic, and aralkyl- 3-,thieny1 thioethers are benzyl, allyl, nonyl, octyl, propyl, butyl, amyl, pinyl, dodecyl, tetradecyl, hexyl, etc.; also, such compounds as 1,2-di-3- thienyl thioethane, 1,2,3-tri-3-thienyl thiopropane, 1,4-di-3-thienyl thiobutane, and the like. This list, of course, is not to be construed as limiting, since the present invention contemplates alkyl, aryl alicyclic, and aralkyl-3-thienyl thioethers generally. Those skilled in the art will readily recognize various other alkyl, aryl, alicyclic, or aralkyl thienyl thioethers which may be synthesized according to the above described procedures.

The preparation of the compounds of the present, invention may be illustrated by the following examples, which are given by way of illustration and not intended to be a limitation on the scope Qt the invention.

EXAMPLE I Preparation of tetradecyled-thienyl thiqether One hundred sixteen grams (1 mole) of 3- thiophenethi'ol, 233 grams ('1 mole) of tetradecylchloride, and 100 milliliters of ethyl alcohol were placed in a flask. A solution of 56' grams of potassium hydroxide in 75 milliliters of water and 150 milliliters of ethyl alcohol was added dropwise over a period of 1 /2 hours with the temperature of the flask being maintained; at 60- C. At the end of this time, the reaction mixture was refluxed for 3' hours. Water was then added and the reaction mixture cooled and filtered. The solid which was thus collected was recrystallized from petroleum ether a number of times. An 80 per cent yield of tetradecyl-3-thienyl ether was obtained. This product had a melting point of 44-45 C., a sulfur content of 20.8 per cent, a carbon content of 69.15 per cent and a hydrogen content of 10.56 per cent. The theoretical sulfur content for the compound is 20.5 per cent. This compound is hereinafter referred to as Compound I.

Preparation of 1,1,3,3-tetramethylbutyl-3- thienyl thioethen One hundred sixteen grams (1; mole) of 3- thiophenethiol and grams of; boron trifluor deee h a e (cc tainine .5 p r ce t, bar itrifl ct x r mixedtoeether and 224, gram (2 moles) of diisobutylene were slowly added.

4 The temperature was maintained at about 45 C. during the addition of the olefin. After complete addition thereof, the mixture was agitated at room temperature for 3 hours. At the end of this time, the reaction product was distilled to give a 7.6 per cent. yield, based on the weight of thiophenethiol of 1,l,3,3-tetramethylbutyl-3- thienyl thioether. This product had a boiling point of l02-.l10 C. at 0.5 millimeters of mercury and a sulfur content of 28.32 per cent, the theoretical sulfur content bein 28.07 per cent. This product is hereinafter referred to as Compound II.

EXAMPLE III Preparation of I-methylheptyL-B-thienul thioether Two hundred thirty-two grams (2 moles) of 3- thiophenethiol and 336 grams (3 moles) of octene-l and 150- grams ofpetroleum ether and grams of a silica-alumina catalyst were placed in a shaking bomb and reacted at a temperature of about 205 C. for a period of 3 hours. At the end of this time, petroleum ether, unreacted thiophenethiol, and unreacted octane-1 were topped off. The remaining product was distilled under vacuum at a temperature of -132 C. at a pressure of 1 millimeter to give 204 grams of 1 methylheptyl-3-thienyl thioether having a sulfur content of 27.5 per cent, the theoretical sulfur content being 28.07 percent. This product is hereinafter referred to as Compound III.

EXAMPLE IV Preparation of benzuZ-3-thienyl thioether Two hundred thirty-two grams (2 moles) of 3, thiophenethiol, 254 grams (2 moles) of benzyl chloride and 200 milliliters of ethyl alcohol were placed in a flask. A solution of 112 grams (2 moles) of potassium hydroxide in milliliters of ethyl alcohol was added dropwise over a period of 7 hours with the temperature of the flask being maintained at 45-50 C. by the heat of reaction. At the end of this time, the reaction mixture was water-washed, dried over magnesium sulfate, and the unreacted materials distilled off. An 81 per cent yield of benzyl-3-thienyl thioether was obtained. After recrystallization from petroleum ether a number of times, the product had a melting point of 37-38 C. and a sulfur content of 31.1 per cent, the. theoretical sulfur content being 31.08 per cent. compound is hereinafter referred to as Compound IV.

EXAMPLE V Preparation of pinyZ-S-thienyl thioether One hundred seventy-five grams (1.5 moles) of 3 -thiophenethiol and 10 grams of boron. triiiuoride-ether complex were placed in a flask. w hun red fir exams (15 mol s.) of a-n nene re dd at. suc a ra e s to ma n a n the temperat re. n thev ra g f 4 0:4,5 t. the. completion or, the reaction, the resultin m x ure as wash ith pot ss um. hydro e sol t on, h w th. water... an finally dr ed. ver. magnesium sulfate. The dried Product wasv then distilled and a 55, per cent yield of pinyl -3-. thienyl thioether was obtained. This compound had a boiling point of 118-122 C at a pressure. of 0.7 millimeter of mercury and a sulfur content of 25.6 per cent, the theoretical sulfur on t ei 2 .5 pe t- T s m ound is'hereinafter referred to as Compound V;

v EXAMPLE VI j Preparation of ,allyl-s-thienyl thioether' Three hundred forty-eight grams (3 moles) of 3-thiophenethiol, 231' grams (3 moles) of allyl chloride, and 300 milliliters of ethyl alcohol were placed in a flask. A solution of 168 grams (3 moles) of potassium hydroxide in 200 milliliters of water and 300 milliliters of ethyl alcohol was added at such a rate that the heat of reaction maintained the temperature of the mixture at about 40 C. The mixture-was then stirred at a temperature of 45 C. for a period of 3 hours after the completion of the addition. The result-'- ing product was then water-washed and dried over magnesium sulfate. Upon distillation, an 86 per cent yield of allyl-3-th-ienyl thioether was obtained. This compound had a boiling point of 50-54 C. at a pressure of 0.4 millimeter of mercury and a sulfur content of 41.2 percent, the theoretical sulfur content being 41.04 per cent. This compound is hereinafter referred to as Compound VI.

EXAMPLE VII Preparation of 2-phenyiethyl-3-thienyl thioether One hundred sixteen grams (1 mole) of 3- thiophenethiol and 104 grams (1 mole) of styrene were mixed. The mixture became quite warm after about 5 minutes of mixing and it was cooled in an ice bath until the temperature had subsided.- After standing at room temperature for several days, the reaction mixture was washed with aqueous potassium hydroxide solution, then with water,'and finallydried over magnesium sulfate. Distillation of the dried mixture resulted in a 67per cent yield of 2- phenylethyl-3-thienyl thioether. This material had a boiling point of 120-122" C. at a pressure of 0.5 millimeter of mercury and a sulfur content of 28.9 per cent, the theoretical sulfur content being 29.10 per cent. This compound is hereinafter referred to as Compound VII.

EXAlWPLE VIII Preparation of n0nyZ-3-thienyl thioether Three hundred thirty-two grams (2.86 moles) of 3-thiophenethiol and grams of boron trifiuoride-ether complex were placed in a flask. To this mixture 378 grams (3 moles) of mixed nonenes were added at such a rate that the temperature of the reaction mixture was maintained atabout 45 C. After the addition of; the nonenes was completed, the reaction mixture was stirred at a temperature of 45-50? C.- for a period of 4 hours. The resulting reactionmixe, ture was washed with potassium hydroxide solution, then with water, and finally dried over magnesium sulfate. Upon distillation .iof the dried reaction mixture, a 52 per centyield of.

nonyl-3-thienyl thioether was obtained. .ThiS compound had a boiling point in the range of 105-110 C. at a pressure of one millimeter of mercury and a sulfur content of 26.6 per cent, the theoretical sulfur content being 26.44 per cent. This compound is hereinafter referred to as Compound VIII.

EXAMPLE IX Preparation of 1,2,3-tri-3-thienyl thiopropane Seventy-five grams (0.5 mole) of 1,2,3-trichloropropane, 203 grams (1.75 .moles) of 3- thiophenethiol, and 150 milliliters of ethyl alcohol were added to a flask. A solution of 98 grams of potassium hydroxide (1.75 molesl in 125 Infill liters of water and 200 milliliters of ethyl alcohol was slowly added to the flask. The temperature was maintained at about 50 C. during this addition. At the end of this time, the resulting reaction mixture was diluted with water and extracted with ethyl ether. The ether solution was then topped to a pot temperature of 100 C. under one millimeter of mercury after first removing the ether at atmospheric pressure. The resulting product had a sulfur content of 41.8 per cent and a chlorine content of 9.26 per cent. This reaction was incomplete, ,so 85 grams of the reaction product were mixed with 50 grams of 3-thiophenethiol and 20 grams of potassium hydroxide in 200 milliliters of ethyl alcohol and heated to a temperature of I C. for a period of 2 hours. After washing with water, drying and topping off the ethyl alcohol, 1,2,3-tri-3-thienyl thiopropane was obtained, having a sulfur content of 49.62 per cent, the theoretical sulfur content being 49.75 per cent. This compound is hereinafter referred to as Compound IX.

EXAMPLE X 7 Preparation of isopropyZ-3-thienyl thioether Two hundred thirty-two grams (2 moles) 'of 3-thiophenethiol, 1'72 grams of isopropyl chloride (2.1 moles) and 112 grams of potassium hydroxide in 300 milliliters of ethyl alcohol and 300 milliliters of water were heated in an autoclave at a temperature of 110-120 C. for one hour. The resulting reaction mixture was extracted with ethyl ether and the ether extract so obtained was washed with HCl and dried over magnesium sulfate. Upon distillation, a 79 per cent yield of isopropyl-3-thieny1 thioether was obtained. This material had a boiling point of 65-66" C. at a pressure of 3 millimeters of mercury and a sulfur content of 39.8 per cent, the theoretical sulfur content being 40.56 per cent. This compound is hereinafter referred to as Compound X.

EXAMPLE XI Preparation of tertiarybutyZ-S-thienyl thioether Eighty-five grams (0.72 mole) of 3-thiophenethiol and 7 cubic centimeters of boron trifiuorideether complex were placed in a flask and iso: butylene was passed through the solution, which was maintained at a temperature between 55 C. and 80 C. After an hour, the addition of isobutylene was stopped. The resulting reaction mixture was washed with watenfiltered, and dried over magnesium sulfate. Upon distillation of the dried reaction mixture, a 42 per, cent yield of tertiarybutyl-3-thienyl thioether wasv obtained. This material had a boiling point of 65-67 C. at one millimeter of mercury and a sulfur content of 36.85 per cent, the theoretical sulfur content being 37.22 per cent. "This One hundred sixteen grams (1 mole) of 3-thiophenethiol and 25 grams of boron trifiuoricleether complex were placed in a flask. Three hundred thirty-six grams (2 moles) of dode'cen were added dropw'ise at such a rate to main-' tain the temperature at about 45 C. After all of the dodecene was added, the reaction mix-' ture was washed-l with -'aqueous potassium laydroxide. solution. then with. wa er. and. finallydried over m nesium ulfa e U on d s ll r tion. a. 60 per cent yield of dodecyl-3-thienyl thioether was obtained. material had a boiling point of 174-176" C. at a pressure of 8 millimeters of mercury and a sulfur content of 23.04; per cent, the theoretical sulfur content being 22.54 per cent. This compound is hereinafter referred to as Compound XII.

EXAMPLE XIII Preparation of wam-Zi-thz'enyl thioether One hundred fifty gram-s (1.3 moles) of 3- thiophenethiol-, 250 grams of chlorowax (containing 11 per cent chlorine) and 200 cubic centimeters of ethyl alcohol were added to a flask. A solution of 84 grams (1.5 moles) of potassium hydroxide in 100 cubic centimeters of water and 200- cubic centimeters of ethyl alcohol was added at such a rate that the temperature was main-- tained in the range or 50-55" C. After the addition of potassium hydroxide solution was completed, the mixture was stirred at a temperature of 75 C. for 2 hours. The resulting. reaction mixture was diluted with water and extrated with petroleum ether. The ether extract so obtained was washed with aqueous potassium hydroxide solution and water, and finally dried over magnesium sulfate. This extract was topped to a pot temperature of 100 C. under one millimeter of mercury to yield wax-E-thienyl thioether having a sulfur content of 21.59 per cent. This compound is hereinafter referred to. as Compound XIII.

EXAMPLE XIV Preparation of 1,2-di-3-th2'eny l t ioethane Four hundred six grams (3.5 moles) of' 3-thi ophenethiol were placed in a flask and 196 gramsof potassium hydroxide (35 moles) in 450 cubic centimeters of ethyl alcohol and 200 cubic centimeters of water were added. Four hundred forty-nine grams (1.5 moles) of ethylene chloride were added at such a rate to maintain the temperature in the range of 45-50 C. After the addition was completed, the reaction mixture was stirred at 75 C. for 5 hours. The resulting reaction mixture was washed well with water and 3'75 grams of white solid formed, representing a yield of 97' per cent of 1,2.-di-.3-thienyl thioethane, based on the weight of ethylene chloride. This material was recrystallized from cyclohexane and had a melting point of 544:5 C. and a sulfur content of 49.41 per cent, the theoretical sulfur content being 49.62 per cent. compound is hereinafter referred to as Compound XIV.

EXAMPLE XV Preparation of 1, 4-di-3-thienyl thiobutane.

Four hundred six grams (3.5 moles) of 3-thiophenethiol and 196 grams of potassium hydroxide in 200 cubicv centimeters of water and 350; cubic centimeters of ethyl alcohol were added to a, flask. One hundred ninety-one grams (1.5 moles) of tetramethylene chloride, were added at such a rate that the temperature was maintained in the range of 45-50 C. After the addition; was comp ed. the tempe re f e mixture was raised to 75 C. and kept there for a period. of s hours. The resulting reaction mixture was w she l i h. water t ive. whi e.gf .a :r rystals of 1,4-di-3-thienyl thiobutane in 87 per cent yield. This, material was recrystallized from cy-.

clohexaneand had a. melting point, of 62-63? Q. 7,5 l-

This

and a sulfur content or; 44.05, per cent, the theoretical sulfur content being 44.62 per cent. This compound is hereinafter referred to as Compound XVI Preparation of 2,4-dinitr0phenyZ-3-thienyl thioether To a. flask Wereadded 6 grams of 3-thiophenethiol dissolved milliliters of ethyl alcohol, 3 grams o o assium yd xid in 15 milliliters f: at and ams o .f r r 0 benr zene in 5Q milliliters of alcohol. The resulting mixture was refluxed for 15 minutes. Water was added to, the resulting reaction mixture. and the product was separated. product of 2,4-dinitrophenylr-il-thienyl thioether was recrystallised several times from ethyl alcohol and had a melting pofmt of 133 C. and a sulfur content of 22.4 per cent. the theoretical sulfur content being 22.71 percent.

The 3-,thienyl thioethers of this invention have been found to be valuable as additives in the stabilization of petroleum oil fractions, particularly in inhibiting the development of those undesirable products and properties such as acid, sludge, discoloration. and corrosiveness toward alloybearing metals normally encountered under conditions of Thus, it is; well known that motor oils, especially those refined by certain solventextraction methods, tend to oxidize when submitted. to high temperatures and to form products that. are corrosive to. metal bearings. This corrosive. action may be, quite severe with certain bearings, such; as those having the corrosion susceptibility of cadmium-silver alloys, and may cause their failure within a comparatively short time. The. following; test was used to determine the corrosive action of a motor oil on an automobile rodbearing.

The oil used consisted of Pennsylvania neutral and residuum stocks separately refined by means of Chlorex and then blended to give an S. A. E. 20 motor oil with a specific gravity of 0.872, a flash point of 435 F. and a Saybolt Universal viscosity of about 318. seconds at 100 F. The oil was tested by adding a section of a bearing containing 22. cadmium-silver alloy surface and weighing about 6- grams, and heating it to C. for 22 hours while a stream of air was bubbled against the surface ofthe bearing. The loss in weight of the bearing during this treatment measures the amount of corrosion that has taken place. A sample of the oilcontaining a stabilizcompound of this invention was run at the same time asa sample of the straight oil and the loss inweight of the bearing section in the inhibited oil can thus be compared directly with the lossin theuninhibited oil. The results obtained in this test employing minor proportions of the above described compounds as inhibitors are set forth in the following table:

Concen- I L trotion, l g. '05! mp Add in Per in Weight Cent test.

A second test to which an oil containing a minor proportion of the compounds of this invention was subjected consisted essentially of passing oxygen through a l50-gram sample of oil at a rate of 2 liters per hour for a period of 70 hours at a temperature of 250 F. and measuring the neutralization number of the oil at the end of the In this test, the base oil containing no additive developed a neutralization number of about 20. The following data indicate that the compounds of this invention are effective in inhibiting the development of acidity in a mineral oil when the same is subjected to oxidation conditions as evidenced by the comparatively low neutralization number of such oils at the completion of the above test. In each of the oils tested, 0.1 per cent by weight of a compound of this invention was incorporated therein.

Neutrali- .zation Number Neutralization Gompound Added Number Compound Added N epp ipp oo ooowooo some: one" From the foregoing test results, it will be evident that the 3-thienyl thioethers of this invention are effective stabilizing agents for petroleum lubrieating oil fractions. The quantity of compound employed as stabilizer to inhibit the undesirable effects of oxidation in the oil may be varied, depending upon the character of the oil and the severity of the conditions to which it is exposed. Ordinarily, the compositions will be added to mineral oil fractions in an amount ranging from about 0.1 to about 4 per cent, but may be added in amounts up to 10 per cent by weight in some instances.

The effectiveness of the above stated minor proportions of 3-thienyl thioethers for stabilizing petroleum lubricating oil fractions is particularly unexpected when it is considered that similar amounts of aliphatic thioethers, such'as didodecyl thioether and dioctylthioether, are ineffective in inhibiting the tendency of oils to corrode metal bearings. Moreover, the thienyl thioethers of this invention give definitely better bearing protection and less oil oxidation than do the corresponding phenyl thioethers. This latter fact is readily brought out by the following comparative test results in which a blank oil, an oil containing a minor proportion of a thienyl thioether and an oil containing the same minor proportion of the corresponding phenyl thioether were subjected to a Lauson engine test. In this test, a single cylinder Lauson engine was run at a speed of 1825 R. P. M. with an oil temperature of 270 F. and a jacket temperature of 212 F. The oil used was an S. A. E. 20 motor oil having a kinematic viscosity of 8.6 at 210 F. The viscosity in oentistokes at 210 F. of the oil and oil blends and the extent of corrosion as measured by the loss in weight of the copperlead hearings were determined after hours. The results are set forth in the table below:

Average weight loss of top and bottom 14 hearings.

It will be observed from the foregoing examples and the results set forth that the 3-thienyl thioethers are uniformly effective in inhibiting the deleterious effects of oxidation upon viscous mineral oil fractions which have been subjected to the various methods of refining treatment currently used. In other words, these compounds are effective as inhibitors in highly refined oils, moderately refined oil, and solvent refined oils.

It is to be understood that the examples, procedures, and oil compositions described hereinabove are illustrative only and are not to be construed as limiting the scope of this invention thereto. Thus, in addition to the specific compounds set forth herein, other 3-thienyl thioethers falling within the scope of the above disclosed general formula may similarly be employed as additives in improving the properties of viscous mineral oil fractions normally subject to deterioration under oxidizing conditions.

This application is a division of copending application Serial No. 791,652, filed December 13, 1947, and issued as U. S. 2,480,832 on September 6, 1949.

We claim:

As a new composition of matter, allyl-3-thienyl thioether.

JOHN W. BROOKS. SIGMUND J. LUKASIEWICZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Evans Dec. 3, 1946 OTHER REFERENCES Number 

